API Usage

I think I'm confused as to how the usage graph works. No matter what I change, it always shows 10k requests at the bottom, and 310 requests in the top. But if I shrink the range to only a week or less (where there are 4k+ requests), it continues to show 10k hits and 310 in the top right.

Is there an easy way to see how many API calls my network has handled? With the start of the billing date quickly approaching (~3 days), I'm afraid I might need to cut off our API access until I can figure out how to accurately measure usage.